Switchgears are a combination of electrical components, such as switches, fuses and circuit breakers, which are used in electrical systems to connect and disconnect all or part of the electrical systems. Electrical cabinets, for example, for a plant, often house one or more switchgears for different electrical systems, operated by one or more sources of power, which are controlled by the switchgears. These switchgears can be provided as plug-in or withdrawable units that are installed into the cabinets so as to electrically connect to main and auxiliary contacts within the cabinet.
In order to prevent accidental touching and dangerous exposure to the active electrical contacts in the cabinet, in particular when inserting or removing withdrawable units, or when not all available spaces within the cabinet are in use, the contacts of the cabinet are covered by an insulating screen. This insulating screen can be a flexible cover or shutter which completely covers the contacts in a closed state and exposes the contacts in an open state. The shutter is formed from an insulating material and protects the contacts from accidental touching until a withdrawable unit is to be installed, during which the shutter opens to expose the contacts and connect the contacts to contact cages of the withdrawable unit in a safe manner. When the withdrawable unit is removed, the shutter transitions again to a closed state. The withdrawable units are used so that it is relatively easy to perform maintenance on switchgears or replace them. To test the protection against direct contact that is provided by the shutter, a test can be performed according to established standards for protection against direct contact and intrusion of foreign particles.
Shutters having various opening and closing mechanisms are known. U.S. Pat. No. 7,067,747 and International Application Publication No. WO 02/087041 describe protective plates which are opened by operating levers. U.S. Pat. No. 6,031,191 describes a protective plate which is opened with pivoting rocker arms. U.S. Patent Application Publication No. 2009/0000926 describes shutter plates that are moved by pivoting-V-shaped linkages attached to a telescoping rod.